Wolfgang Petrusch 21.11.2002
36-WG11/Capetown/133
Comments to 815 Part 1 and Part 2 The following comments are based on the documents 36/187/CD (815-1), 36/191/CD (815-2), Capetown/129 and Capetown/130.
815-1 Proposal for clause 3.6: .........divided by the maximum operating voltage (for a.c. systems usually Um/√3) across........ Proposal for clause 10.2: Aerodynamic or open profiles prove to be beneficial in areas where the pollution is deposited onto the insulator by wind, such as deserts, heavily polluted industrial areas or coastal areas which are not directly exposed to salt spray. This type of profile is especially effective in areas that are characterised by extended dry periods. Open profiles are also accessible for easy cleaning under maintenance. Standard profiles are effective for use in “very light“ or “medium“ polluted areas where a long creepage distance or aerodynamical effective profile is not required. The use of fog-type (anti fog) profiles with steeper shed inclination or with under-ribs, are beneficial in areas exposed to a salt water fog or spray, or to other pollutants in the dissolved state. These profiles may also be effective in areas with a particulate pollution precipitation containing slow dissolving salts. Alternating long and short sheds are beneficial in areas where heavy wetting can occur. An alternating housing profile can be designed in general with all kinds of shed profiles. More advice on profiles is given in the relevant further parts of this publication.
-2-
Proposal for Figure 1 (missing figures will follow as wmf-file):
Open profile
Standard profile
DIN profile
Fog-type profile
Figure 1a – Typical porcelain post, long rod and hollow insulator shed profiles.
Figure 1b (unchanged)
Open profile
Inclined profile
Under ribbed profile
Figure 1c – Typical polymeric line insulator, line post and hollow insulator profiles.
Alternating profile (porcelain, polymer)
Steep inclined profile (porcelain)
Figure 1d – Typical variants for post, long rod, line post and hollow insulators.
-3-
815-2 Proposal for clause 3.1: Take over the proposal for 815-1 clause 3.6.
Proposal for clause 9.1: Aerodynamic or open profiles prove to be beneficial in areas where the pollution is deposited onto the insulator by wind, such as deserts, heavily polluted industrial areas or coastal areas which are not directly exposed to salt spray. This type of profile is especially effective in areas that are characterised by extended dry periods. Open profiles are also accessible for easy cleaning under maintenance. Standard profiles are effective for use in “very light“ or “medium“ polluted areas where a long creepage distance or aerodynamical effective profile is not required. The use of fog-type (anti fog) profiles with steeper shed inclination or with under-ribs, are beneficial in areas exposed to a salt water fog or spray, or to other pollutants in the dissolved state. These profiles may also be effective in areas with a particulate pollution precipitation containing slow dissolving salts. Alternating long and short sheds are beneficial in areas where heavy wetting can occur. An alternating housing profile can be designed in general with all kinds of shed profiles. See Figures 2 to 4 for definition of the described profile types. Proposal for Figure 2 (missing figures will follow as wmf-file):
Open profile
Standard profile
DIN profile
Fog-type profile
Figure 2a – Typical porcelain post, long rod and hollow insulator shed profiles.
Alternating profile (can be designed for any profile type shown)
Steep inclined profile
Figure 2b – Typical variants for porcelain post, long rod, line post and hollow insulators.
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Comments on Table 1 to 4: Under the viewpoint that the marks in the tables are used for determination of the profile correction factor Kps , the tables should be checked again. The explanations in columns 2 to 4 should be deleted. Proposal for Table 3: Table 3:
The selection of profile for vertical a.c. long rod, post and hollow insulators
Polluted Areas Desert
Open Profile
Standard Profile
Fog-type Profile
Areas with sandy soils or in a desert location. These areas can be extensive polluted. Pollution that dissolves slowly has a high inert component, mainly wind borne.
Coastal Areas in direct vicinity of the coast, but in some cases can be as far inland as 10-20 km inland. Rapid pollution build-up and effective washing (not very adhesive). Quick dissolving pollution. Has low inert component. Pollution by wind and gravity.
Industrial/Agriculture Areas in close proximity to the industrial pollution source, may only affect a few installations. Conductive particulate pollution. (Cement, coal, chemicals, NOx, SOx etc. Pollution that dissolves slowly has medium or high inert component, often heavy particles which settle on horizontal surfaces.
Inland (Low Pollution)
Alternating shed profiles may have advantages under heavy wetting conditions. Alternating shed profiles can be designed for the specific pollution area with all 3 profile types (“open“, “standard“, “fog-type“) to consider also heavy rain conditions. Recommended
Acceptable
Unsuitable
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Proposal for Table 4: Table 4:
The selection of profile for horizontal a.c. long rod, post and hollow insulators
Polluted Areas Desert
Open Profile
Standard Profile
Fog-type Profile
Areas with sandy soils or in a desert location. These areas can be extensive polluted. Pollution that dissolves slowly has a high inert component, mainly wind borne.
Coastal Areas in direct vicinity of the coast, but in some cases can be as far inland as 10-20 km inland. Rapid pollution build-up and effective washing (not very adhesive). Quick dissolving pollution. Has low inert component. Pollution by wind and gravity.
Industrial/Agriculture Areas in close proximity to the industrial pollution source, may only affect a few installations. Conductive particulate pollution. (Cement, coal, chemicals, NOx, SOx etc. Pollution that dissolves slowly has medium or high inert component, often heavy particles which settle on horizontal surfaces.
Inland (Low Pollution)
Recommended
Acceptable
Unsuitable
